Tissue-based water barrier material

ABSTRACT

A hydrophobic, liquid-impermeable substrate includes a hydrophilic nonwoven having a treated surface, a polyolefin dispersion disposed on the treated surface, and a hydrophobic chemistry disposed on the polyolefin dispersion. A method for preparing a hydrophobic, breathable, liquid-impermeable substrate includes providing a hydrophilic nonwoven having a treated surface, applying a polyolefin dispersion to the treated surface, and applying a hydrophobic chemistry to the polyolefin dispersion. The hydrophilic nonwoven can be tissue or paper toweling. The hydrophobic chemistry can be a water-dispersible hydrophobic polymer.

BACKGROUND

The present disclosure relates to hydrophilic, breathable materials thatexhibit hydrophobic properties when treated with certain compositions.Currently, hydrophobic, breathable materials are generally made usinghydrophobic polymeric films or fiber webs. Such materials tend to behydrophobic throughout the thickness of the material, which might not bedesired in many cases. Such materials also tend to be less costeffective. Although various formulated dispersions capable of coating asurface to make that surface hydrophobic exist, these tend not to bewater-based. These tend to require the use of organic solvents.

Disposable absorbent products (e.g., diapers, feminine hygiene products,incontinence products, etc.) are subjected to one or more liquidinsults, such as of water, urine, menses, or blood, during use. Manycommercially available diapers allow water vapor to pass through thediaper and into the environment to lessen the humidity in themicro-climate between the product and the wearer's skin and reduce thechance of skin irritation and rash due to skin overhydration. To allowthe passage of vapor out of the diaper and into the environment whileholding liquid within, a “breathable” outer cover is often employed thatis formed from a nonwoven web laminated to a vapor-permeable film.

SUMMARY

As a result, a new material is needed that is both cost-effective anddoes not rely on organic solvents. The present disclosure relates to theuse of a hydrophobic chemistry applied to a hydrophilic fibrous materialto create liquid barrier properties in an otherwise wettable nonwoven.This yields a hydrophilic substrate that acts like a film while stillbeing air permeable and exceeding the breathability seen in standardbreathable outer cover films.

Presented is a hydrophobic, liquid-impermeable substrate including ahydrophilic nonwoven having a treated surface, a polyolefin dispersiondisposed on the treated surface, and a hydrophobic chemistry disposed onthe polyolefin dispersion. The hydrophilic nonwoven can be tissue orpaper toweling. The hydrophobic chemistry can be a water-dispersiblehydrophobic polymer.

In another aspect, a method for preparing a hydrophobic, breathable,liquid-impermeable substrate includes providing a hydrophilic nonwovenhaving a treated surface, applying a polyolefin dispersion to thetreated surface, and applying a hydrophobic chemistry to the polyolefindispersion.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and other features and aspects of the present disclosureand the manner of attaining them will become more apparent, and thedisclosure itself will be better understood by reference to thefollowing description, appended claims and accompanying drawings, where:

FIG. 1 illustrates hydrohead behavior for Substrate A and Substrate B asa function of increasing add-on amounts of hydrophobic chemistries;

FIG. 2 illustrates hydrohead behavior for sized handsheets. Note thatlines are not a mathematical trend but are included to show a generalbehavior;

FIG. 3 illustrates the behavior of Substrate B with a HYPOD polyolefindispersion and hydrophobic chemistries in the functional water barriertest;

FIG. 4 illustrates the behavior of Substrate A with a HYPOD polyolefindispersion and hydrophobic chemistries in the functional water barriertest;

FIG. 5 illustrates leakage from handsheets in a functional water barriertest. The hydrophobic add-ons were approximately 0.1 gsm for nanoclayand 2 gsm for the UNIDYNE KCO3 fluorinated water and oil repellent. Notethat the lines are not mathematical trends;

FIG. 6 illustrates the air permeability of various basesheets. The airpermeability of an ASFL outer cover is zero;

FIG. 7 illustrates hydrohead versus leakage. Hydrohead is in centimetersof water and leakage is in grams from the functional water barrier test(FWBT). The FWBT was performed with 0.2 psi, 90% core capacity, and aone-minute wait before applying pressure;

FIG. 8 illustrates hydrohead versus air permeability; and

FIG. 9 illustrates the test apparatus for measuring hydrohead values.

Repeat use of reference characters in the present specification anddrawings is intended to represent the same or analogous features orelements of the present disclosure. The drawings are representationaland are not necessarily drawn to scale. Certain proportions thereofmight be exaggerated, while others might be minimized.

DETAILED DESCRIPTION

All percentages are by weight of the total composition unlessspecifically stated otherwise. All ratios are weight ratios unlessspecifically stated otherwise.

The term “hydrophobic,” as used herein, refers to the property of asurface to repel water with a water contact angle greater than about90°.

The term “superhydrophobic” refers to the property of a surface to repelwater very effectively. This property is quantified by a water contactangle generally exceeding 150°.

The term “hydrophilic,” as used herein, refers to surfaces with watercontact angles well below 90°.

As used herein, the term “breathability” refers to the water vaportransmission rate (WVTR) of an area of film. Breathability is measuredin grams of water per square meter per day. For purposes of the presentdisclosure, a film is “breathable” if it has a WVTR of at least 800grams per square meter per 24 hours as calculated using the MOCON testmethod, which is described in detail below.

As used herein, the term “nonwoven web” or “nonwoven fabric” means a webhaving a structure of individual fibers or threads that are interlaid,but not in an identifiable manner as in a knitted web. Nonwoven webshave been formed from many processes, such as, for example, meltblowingprocesses, spunbonding processes, air-laying processes, coformingprocesses, bonded carded web processes, and tissue and towelmanufacturing processes. The basis weight of nonwoven webs is usuallyexpressed in ounces of material per square yard (osy) or grams persquare meter (gsm) and the fiber diameters are usually expressed inmicrons, or in the case of staple fibers, in denier. It is noted that toconvert from osy to gsm, multiply osy by 33.91.

As used herein the term “spunbond fibers” refers to small diameterfibers of molecularly oriented polymeric material. Spunbond fibers canbe formed by extruding molten thermoplastic material as fibers from aplurality of fine, usually circular capillaries of a spinneret with thediameter of the extruded fibers then being rapidly reduced as in, forexample, U.S. Pat. No. 4,340,563 to Appel et al., and U.S. Pat. No.3,692,618 to Dorschner et al., U.S. Pat. No. 3,802,817 to Matsuki etal., U.S. Pat. Nos. 3,338,992 and 3,341,394 to Kinney, U.S. Pat. No.3,502,763 to Hartman, U.S. Pat. No. 3,542,615 to Dobo et al, and U.S.Pat. No. 5,382,400 to Pike et al. Spunbond fibers are generally nottacky when they are deposited onto a collecting surface and aregenerally continuous. Spunbond fibers are often about 10 microns orgreater in diameter. However, fine fiber spunbond webs (having anaverage fiber diameter less than about 10 microns) can be achieved byvarious methods including, but not limited to, those described incommonly assigned U.S. Pat. No. 6,200,669 to Marmon et al. and U.S. Pat.No. 5,759,926 to Pike et al.

Meltblown nonwoven webs are prepared from meltblown fibers. As usedherein the term “meltblown fibers” means fibers formed by extruding amolten thermoplastic material through a plurality of fine, usuallycircular, die capillaries as molten threads or filaments into converginghigh velocity, usually hot, gas (e.g. air) streams that attenuate thefilaments of molten thermoplastic material to reduce their diameter,which can be to microfiber diameter. Thereafter, the meltblown fibersare carried by the high velocity gas stream and are deposited on acollecting surface to form a web of randomly dispersed meltblown fibers.Such a process is disclosed, for example, in U.S. Pat. No. 3,849,241 toBuntin. Meltblown fibers are microfibers that can be continuous ordiscontinuous, are generally smaller than 10 microns in average diameter(using a sample size of at least 10), and are generally tacky whendeposited onto a collecting surface.

As used herein, the term “polymer” generally includes, but is notlimited to, homopolymers, copolymers, such as for example, block, graft,random and alternating copolymers, terpolymers, etc. and blends andmodifications thereof. Furthermore, unless otherwise specificallylimited, the term “polymer” shall include all possible geometricalconfigurations of the molecule. These configurations include, but arenot limited to isotactic, syndiotactic and random symmetries.

As used herein, the term “multicomponent fibers” refers to fibers orfilaments that have been formed from at least two polymers extruded fromseparate extruders but spun together to form one fiber. Multicomponentfibers are also sometimes referred to as “conjugate” or “bicomponent”fibers or filaments. The term “bicomponent” means that there are twopolymeric components making up the fibers. The polymers are usuallydifferent from each other, although conjugate fibers can be preparedfrom the same polymer, if the polymer in each component is differentfrom one another in some physical property, such as, for example,melting point, glass transition temperature or the softening point. Inall cases, the polymers are arranged in substantially constantlypositioned distinct zones across the cross-section of the multicomponentfibers or filaments and extend continuously along the length of themulticomponent fibers or filaments. The configuration of such amulticomponent fiber can be, for example, a sheath/core arrangement,wherein one polymer is surrounded by another, a side-by-sidearrangement, a pie arrangement or an “islands-in-the-sea” arrangement.Multicomponent fibers are taught in U.S. Pat. No. 5,108,820 to Kaneko etal.; U.S. Pat. No. 5,336,552 to Strack et al.; and U.S. Pat. No.5,382,400 to Pike et al. For two component fibers or filaments, thepolymers can be present in ratios of 75/25, 50/50, 25/75 or any otherdesired ratios.

As used herein, the term “multiconstituent fibers” refers to fibers thathave been formed from at least two polymers extruded from the sameextruder as a blend or mixture. Multiconstituent fibers do not have thevarious polymer components arranged in relatively constantly positioneddistinct zones across the cross-sectional area of the fiber and thevarious polymers are usually not continuous along the entire length ofthe fiber, instead usually forming fibrils or protofibrils that startand end at random. Fibers of this general type are discussed in, forexample, U.S. Pat. Nos. 5,108,827 and 5,294,482 to Gessner.

As used herein, the term “substantially continuous fibers” is intendedto mean fiber that have a length that is greater that the length ofstaple fibers. The term is intended to include fibers that arecontinuous, such as spunbond fibers, and fibers that are not continuous,but have a defined length greater than about 150 millimeters.

As used herein, the term “staple fibers” means fibers that have a fiberlength generally in the range of about 0.5 to about 150 millimeters.Staple fibers can be cellulosic fibers or non-cellulosic fibers. Someexamples of suitable non-cellulosic fibers that can be used include, butare not limited to, polyolefin fibers, polyester fibers, nylon fibers,polyvinyl acetate fibers, and mixtures thereof. Cellulosic staple fibersinclude for example, pulp, thermomechanical pulp, synthetic cellulosicfibers, modified cellulosic fibers, and the like. Cellulosic fibers canbe obtained from secondary or recycled sources. Some examples ofsuitable cellulosic fiber sources include virgin wood fibers, such asthermomechanical, bleached and unbleached softwood and hardwood pulps.Secondary or recycled cellulosic fibers can be obtained from officewaste, newsprint, brown paper stock, paperboard scrap, etc., can also beused. Further, vegetable fibers, such as abaca, flax, milkweed, cotton,modified cotton, cotton linters, can also be used as the cellulosicfibers. In addition, synthetic cellulosic fibers such as, for example,rayon and viscose rayon can be used. Modified cellulosic fibers aregenerally are composed of derivatives of cellulose formed bysubstitution of appropriate radicals (e.g., carboxyl, alkyl, acetate,nitrate, etc.) for hydroxyl groups along the carbon chain.

As used herein, the term “pulp” refers to fibers from natural sourcessuch as woody and non-woody plants. Woody plants include, for example,deciduous and coniferous trees. Non-woody plants include, for example,cotton, flax, esparto grass, milkweed, straw, jute, hemp, and bagasse.

As used herein, “tissue products” are meant to include facial tissue,bath tissue, towels, hankies, napkins and the like. The presentdisclosure is useful with tissue products and tissue paper in general,including but not limited to conventionally felt-pressed tissue paper,high bulk pattern densified tissue paper, and high bulk, uncompactedtissue paper.

The present disclosure relates to a surface of a hydrophilic substrate,or the substrate itself, exhibiting hydrophobic characteristics whentreated with certain compositions. The hydrophobicity can be appliedeither over the entire surface, patterned throughout or on the substratematerial, and/or directly penetrated through the z-directional thicknessof the substrate material.

Materials such as diaper outercover spunbond-film laminate or surgicalgown SMS are currently used to prevent liquid from penetrating throughthe material and onto the user or into the user's environment. Thesematerials use film or meltblown made from hydrophobic polymers asbarrier materials to prevent fluid penetration. On the other hand, manyhydrophilic materials are currently used in various applications, thematerials including those such as coform and HYDROKNIT brand towel(available from Kimberly-Clark) for wipes as well as cellulosic tissuesfor facial and bath tissues. These materials are absorptive and thus notuseful as barriers to aqueous fluids. Tissue-based materials tend to beless expensive than polymeric laminates and films. Therefore, it wouldbe desirable to use these as barrier materials if adequate function canbe engineered.

The primary functions of a diaper outer cover are to isolate thecontents of the inside of a diaper (e.g. body fluids) from theenvironment and to keep the entire product together over its useful lifethrough disposal. Film-based substrates have been the choicehistorically because they can achieve this function at a low cost with awidely available material—polyethylene film. Over time, several featureshave been added to the outer cover including breathability (for skinhealth), cloth-like feel (tactile consumer benefit) and graphics (visualconsumer aesthetics). This has necessitated an increase in base cost ofthe outer cover due to additional materials, process steps, and handlingrequirements. The materials described herein chooses a differentstarting point—a porous tissue-based substrate—to study the possibilityof producing a material with a barrier function while maintainingbreathability and not significantly increasing cost. In addition, tissuemight be more widely available, particularly globally. This disclosurefocuses on the outer cover portion of a diaper, and how to developtissue that provides a water barrier such that it can function as anouter cover. Tissue is typically a highly absorbent, highly porousmaterial that is unusable as a water barrier.

Three basic aspects of functionality that are important to understandand influence are 1) breathability—greater than a threshold vaporpermeability; 2) liquid barrier—resistant to liquid transfer from asaturated absorbent; and 3) durability—abrasion and poke-throughresistance.

The durability requirement stems from the need to keep the productcontents together through the life of the article. The most stringentrequirements likely are when the absorbent is saturated and the outercover is subjected to deformation in use. Breathability is likely not anissue with this approach except that it can be too high such that thereis a damp feel. Prior work has described how to mitigate this effect,see U.S. Pat. No. 6,369,292, which is incorporated herein by referenceto the extent is does not conflict herewith. Liquid barrier is achallenge that is particularly tough for this approach because thestarting point is a porous material that can be naturally hydrophilic.Surface energetics and pore size need to be controlled to ensure thatthe fabric has sufficient fluid transfer resistance.

Barrier performance with air permeability can be accomplished by coatinga hydrophilic, fibrous substrate with both a polyolefin dispersion and ahydrophobic component. It was found that a combination of two treatmentsprovided the desired benefits on a tissue/towel-based substrate. Thebest performance observed was the use of Substrate A, a double recrepedtissue with printed latex and creped on both sides as described in U.S.Pat. No. 6,277,241, which is incorporated herein by reference to theextent it does not conflict herewith, and sold commercially as SCOTTbrand scrub cloths. Substrate B is an UCTAD tissue with printed latexand creped on one side as described in U.S. Pat. No. 7,462,258, which isincorporated herein by reference to the extent it does not conflictherewith, and sold commercially as VIVA brand paper towels.

The first step is coating the substrate with a polyolefin dispersionsuch as a polyethylene copolymer dispersion commercially available asHYPOD 8510 from Dow Chemical, Freeport, Tex., U.S.A., as described inmore detail below. This can be done via standard application methodsincluding spray/crepe and foam/crepe processes such as those describedin U.S. Patent Publication Nos. US20070137810, US20070137809, andUS20120160400, and in U.S. patent application Ser. No. 13/905,429, eachof which is incorporated herein by reference to the extent it does notconflict herewith. Uniformity of this coating step is important toensure uniformity of the subsequent treatment in the second step.

The second step is coating the polymeric-dispersion treated substratewith a hydrophobic chemistry, as described in more detail below. Suchhydrophobic chemistries can include Daikin UNIDYNE KCO3 fluorinatedwater and oil repellent, Formulation III, or Formulation V describedbelow. UNIDYNE KCO3 fluorinated water and oil repellent is a chemicalproduced by Daikin America. Formulation III is 5 percent PMC, a 20 wt. %dispersion of a fluorinated ethylene-acrylic copolymer in water, asobtained from DUPONT (trade name CAPSTONE ST-100), and 95 percent water.Formulation V is PMC, water, and a hydrophilic nano-structured filler(NANOMER brand PGV nanoclay from Sigma Aldrich), which is a bentoniteclay without organic modification. In Formulation V, the hydrophilicnanoclay is added to water and is sonicated until a stable suspension isproduced. Formulations III and V are further described in U.S. patentapplication Ser. No. 13/193,065, which is incorporated herein byreference to the extent it does not conflict herewith.

The approach that was taken in this work was to experiment withadditives and treatments that have been used previously to impart waterbarriers. The additives used were various sizing chemistries that tendto make the bulk hydrophobic. To provide a barrier function, only thesurface of a substrate needs to be hydrophobic. As a result, the bulkapproach is inefficient in terms of the level of chemistry added.However, additives in the wet end are easy to incorporate compared tosurface treatments. The treatments used include a polyolefin dispersionapplied using creping and several hydrophobic treatments that wereapplied by spray. Both the additive and treatment approaches rely oncreating hydrophobic surfaces in the substrate. These need to becomplemented with small pore size within the substrate as well tomaintain good barrier. Sheet density and size of fibers used to form thesubstrate, for example, are well known ways to control pore size.

Several examples are detailed herein, leading to the conclusion that thecombination of the polyolefin dispersion and hydrophobic treatmentsyields unexpected benefits, where one or the other treatment alone doesnot provide the desired benefits.

Suitable substrates of the present disclosure can include a nonwovenfabric, woven fabric, knit fabric, or laminates of these materials, toinclude a tissue or towel, as described herein. Materials and processessuitable for forming such substrate are generally well known to thoseskilled in the art. For instance, some examples of nonwoven fabrics thatcan be used in the present disclosure include, but are not limited to,spunbonded webs, meltblown webs, bonded carded webs, air-laid webs,coform webs, spunlace nonwoven web, hydraulically entangled webs, andthe like. In each case, at least one of the fibers used to prepare thenonwoven fabric is a thermoplastic material containing fiber. Inaddition, nonwoven fabrics can be a combination of thermoplastic fibersand natural fibers, such as, for example, cellulosic fibers (softwoodpulp, hardwood pulp, thermomechanical pulp, etc.). Generally, from thestandpoint of cost and desired properties, the substrate of the presentdisclosure is a hydrophilic nonwoven fabric.

If desired, the nonwoven fabric can also be bonded using techniques wellknown in the art to improve the durability, strength, hand, aesthetics,texture, and/or other properties of the fabric. For instance, thenonwoven fabric can be thermally (e.g., pattern bonded, through-airdried), ultrasonically, adhesively and/or mechanically (e.g. needled)bonded. For instance, various pattern bonding techniques are describedin U.S. Pat. No. 3,855,046 to Hansen; U.S. Pat. No. 5,620,779 to Levy,et al.; U.S. Pat. No. 5,962,112 to Haynes, et al.; U.S. Pat. No.6,093,665 to Sayovitz, et al.; U.S. Design Pat. No. 428,267 to Romano,et al.; and U.S. Design Pat. No. 390,708 to Brown.

In another aspect, the substrate of the present disclosure is formedfrom a spunbonded web containing monocomponent and/or multicomponentfibers. Multicomponent fibers are fibers that have been formed from atleast two polymer components. Such fibers are usually extruded fromseparate extruders but spun together to form one fiber. The polymers ofthe respective components are usually different from each other althoughmulticomponent fibers can include separate components of similar oridentical polymeric materials. The individual components are typicallyarranged in substantially constantly positioned distinct zones acrossthe cross-section of the fiber and extend substantially along the entirelength of the fiber. The configuration of such fibers can be, forexample, a side-by-side arrangement, a pie arrangement, or any otherarrangement.

When used, multicomponent fibers can also be splittable. In fabricatingmulticomponent fibers that are splittable, the individual segments thatcollectively form the unitary multicomponent fiber are contiguous alongthe longitudinal direction of the multicomponent fiber in a manner suchthat one or more segments form part of the outer surface of the unitarymulticomponent fiber. In other words, one or more segments are exposedalong the outer perimeter of the multicomponent fiber. For example,splittable multicomponent fibers and methods for making such fibers aredescribed in U.S. Pat. No. 5,935,883 to Pike and U.S. Pat. No. 6,200,669to Marmon, et al.

The substrate of the present disclosure can also contain a coformmaterial. The term “coform material” generally refers to compositematerials including a mixture or stabilized matrix of thermoplasticfibers and a second non-thermoplastic material. As an example, coformmaterials can be made by a process in which at least one meltblown diehead is arranged near a chute through which other materials are added tothe web while it is forming. Such other materials can include, but arenot limited to, fibrous organic materials such as woody or non-woodypulp such as cotton, rayon, recycled paper, pulp fluff and alsosuperabsorbent particles, inorganic absorbent materials, treatedpolymeric staple fibers and the like. Some examples of such coformmaterials are disclosed in U.S. Pat. No. 4,100,324 to Anderson, et al.;U.S. Pat. No. 5,284,703 to Everhart, et al.; and U.S. Pat. No. 5,350,624to Georger, et al.

Additionally, the substrate can also be formed from a material that isimparted with texture one or more surfaces. For instance, in someaspects, the substrate can be formed from a dual-textured spunbond ormeltblown material, such as described in U.S. Pat. No. 4,659,609 toLamers, et al. and U.S. Pat. No. 4,833,003 to Win, et al.

In one particular aspect of the present disclosure, the substrate isformed from a hydroentangled nonwoven fabric. Hydroentangling processesand hydroentangled composite webs containing various combinations ofdifferent fibers are known in the art. A typical hydroentangling processutilizes high pressure jet streams of water to entangle fibers and/orfilaments to form a highly entangled consolidated fibrous structure,e.g., a nonwoven fabric. Hydroentangled nonwoven fabrics of staplelength fibers and continuous filaments are disclosed, for example, inU.S. Pat. No. 3,494,821 to Evans and U.S. Pat. No. 4,144,370.Hydroentangled composite nonwoven fabrics of a continuous filamentnonwoven web and a pulp layer are disclosed, for example, in U.S. Pat.No. 5,284,703 to Everhart, et al. and U.S. Pat. No. 6,315,864 toAnderson, et al.

Of these nonwoven fabrics, hydroentangled nonwoven webs with staplefibers entangled with thermoplastic fibers is especially suited as thesubstrate. In one particular example of a hydroentangled nonwoven web,the staple fibers are hydraulically entangled with substantiallycontinuous thermoplastic fibers. The staple can be cellulosic staplefiber, non-cellulosic staple fibers or a mixture thereof. Suitablenon-cellulosic staple fibers includes thermoplastic staple fibers, suchas polyolefin staple fibers, polyester staple fibers, nylon staplefibers, polyvinyl acetate staple fibers, and the like or mixturesthereof. Suitable cellulosic staple fibers include for example, pulp,thermomechanical pulp, synthetic cellulosic fibers, modified cellulosicfibers, and the like. Cellulosic fibers can be obtained from secondaryor recycled sources. Some examples of suitable cellulosic fiber sourcesinclude virgin wood fibers, such as thermomechanical, bleached andunbleached softwood and hardwood pulps. Secondary or recycled cellulosicfibers can be obtained from office waste, newsprint, brown paper stock,paperboard scrap, etc., can also be used. Further, vegetable fibers,such as abaca, flax, milkweed, cotton, modified cotton, cotton linters,can also be used as the cellulosic fibers. In addition, syntheticcellulosic fibers such as, for example, rayon and viscose rayon can beused. Modified cellulosic fibers are generally composed of derivativesof cellulose formed by substitution of appropriate radicals (e.g.,carboxyl, alkyl, acetate, nitrate, etc.) for hydroxyl groups along thecarbon chain.

One particularly suitable hydroentangled nonwoven web is a nonwoven webcomposite of polypropylene spunbond fibers, which are substantiallycontinuous fibers, having pulp fibers hydraulically entangled with thespunbond fibers. Another particularly suitable hydroentangled nonwovenweb is a nonwoven web composite of polypropylene spunbond fibers havinga mixture of cellulosic and non-cellulosic staple fibers hydraulicallyentangled with the spunbond fibers.

The substrate of the present disclosure can be prepared solely fromthermoplastic fibers or can contain both thermoplastic fibers andnon-thermoplastic fibers. Generally, when the substrate contains boththermoplastic fibers and non-thermoplastic fibers, the thermoplasticfibers make up from about 10% to about 90%, by weight of the substrate.In a particular aspect, the substrate contains between about 10% andabout 30%, by weight, thermoplastic fibers.

For this disclosure, a nonwoven substrate will have a basis weight inthe range of about 10 gsm (grams per square meter) to about 200 gsm,more typically, between about 15 gsm to about 150 gsm. For particularlysuitable substrates, the basis weight will be in the 20 gsm to 50 gsmrange.

The thermoplastic materials or fibers making-up at least a portion ofthe substrate can essentially be any thermoplastic polymer. Suitablethermoplastic polymers include polyolefins, polyesters, polyamides,polyurethanes, polyvinylchloride, polytetrafluoroethylene, polystyrene,polyethylene terephthalate, biodegradable polymers such as polylacticacid and copolymers and blends thereof. Suitable polyolefins includepolyethylene, e.g., high density polyethylene, medium densitypolyethylene, low density polyethylene and linear low densitypolyethylene; polypropylene, e.g., isotactic polypropylene, syndiotacticpolypropylene, blends of isotactic polypropylene and atacticpolypropylene, and blends thereof; polybutylene, e.g., poly(l-butene)and poly(2-butene); polypentene, e.g., poly(l-pentene) andpoly(2-pentene); poly(3-methyl-1-pentene); poly(4-methyl 1-pentene); andcopolymers and blends thereof. Suitable copolymers include random andblock copolymers prepared from two or more different unsaturated olefinmonomers, such as ethylene/propylene and ethylene/butylene copolymers.Suitable polyamides include nylon 6, nylon 6/6, nylon 4/6, nylon 11,nylon 12, nylon 6/10, nylon 6/12, nylon 12/12, copolymers of caprolactamand alkylene oxide diamine, and the like, as well as blends andcopolymers thereof. Suitable polyesters include polyethyleneterephthalate, polytrimethylene terephthalate, polybutyleneterephthalate, polytetramethylene terephthalate,polycyclohexylene-1,4-dimethylene terephthalate, and isophthalatecopolymers thereof, as well as blends thereof. These thermoplasticpolymers can be used to prepare both substantially continuous fibers andstaple fibers, in accordance with the present disclosure.

In another aspect, the substrate can be a tissue product. The tissueproduct can be of a homogenous or multi-layered construction, and tissueproducts made therefrom can be of a single-ply or multi-plyconstruction. The tissue product desirably has a basis weight of about10 g/m2 to about 65 g/m2, and density of about 0.04 g/cc or more. Moredesirably, the basis weight will be about 40 g/m2 or less and thedensity will be about 0.2 g/cc or more. Most desirably, the density willbe about 0.3 g/cc or more. Unless otherwise specified, all amounts andweights relative to the paper are on a dry basis. Tensile strengths inthe machine direction can be in the range of from about 100 to about5,000 grams per inch of width. Tensile strengths in the cross-machinedirection are from about 50 grams to about 2,500 grams per inch ofwidth. Absorbency is typically from about 5 grams of water per gram ofsubstrate to about 9 grams of water per gram of substrate prior to anytreatment being applied.

Conventionally pressed tissue products and methods for making suchproducts are well known in the art. Tissue products are typically madeby depositing a papermaking furnish on a foraminous forming wire, oftenreferred to in the art as a Fourdrinier wire. Once the furnish isdeposited on the forming wire, it is referred to as a web. The web isdewatered by pressing the web and drying at elevated temperature. Theparticular techniques and typical equipment for making webs according tothe process just described are well known to those skilled in the art.In a typical process, a low consistency pulp furnish is provided from apressurized headbox, which has an opening for delivering a thin depositof pulp furnish onto the Fourdrinier wire to form a wet web. The web isthen typically dewatered to a fiber consistency of from about 7% toabout 25% (total web weight basis) by vacuum dewatering and furtherdried by pressing operations wherein the web is subjected to pressuredeveloped by opposing mechanical members, for example, cylindricalrolls. The dewatered web is then further pressed and dried by a steamdrum apparatus known in the art as a Yankee dryer. Pressure can bedeveloped at the Yankee dryer by mechanical means such as an opposingcylindrical drum pressing against the web. Multiple Yankee dryer drumscan be employed, whereby additional pressing is optionally incurredbetween the drums. The formed sheets are considered to be compactedbecause the entire web is subjected to substantial mechanicalcompressional forces while the fibers are moist and are then dried whilein a compressed state.

One particular aspect of the present disclosure utilizes an uncrepedthrough-air-drying technique to form the tissue product.Through-air-drying can increase the bulk and softness of the web.Examples of such a technique are disclosed in U.S. Pat. No. 5,048,589 toCook, et al.; U.S. Pat. No. 5,399,412 to Sudall, et al.; U.S. Pat. No.5,510,001 to Hermans, et al.; U.S. Pat. No. 5,591,309 to Ruqowski, etal.; U.S. Pat. No. 6,017,417 to Wendt, et al., and U.S. Pat. No.6,432,270 to Liu, et al. Uncreped through-air-drying generally involvesthe steps of: (1) forming a furnish of cellulosic fibers, water, andoptionally, other additives; (2) depositing the furnish on a travelingforaminous belt, thereby forming a fibrous web on top of the travelingforaminous belt; (3) subjecting the fibrous web to through-air-drying toremove the water from the fibrous web; and (4) removing the driedfibrous web from the traveling foraminous belt.

Polyolefin Dispersion

HYPOD 8510 polyolefin dispersion is a DOW Chemical product that can beused to provide softness for the facial tissue. HYPOD polyolefindispersion is a polyolefin dispersion; polyolefin dispersions typicallyhave very low surface energy and do not wet out well, are inertchemically, and are water based. Some advantages of the polyolefindispersion are 1) water resistance, 2) oil and grease resistance, 3)heat seal ability, 4) low temperature flexibility, and 5) it can beapplied using low viscosity methods such as spraying, printing, andfoaming. The ethylene octene copolymer contributes softness and theethylene acrylic acid is the binder that keeps the particles fromagglomerating in the dispersion. The use of HYPOD polyolefin dispersionis further described in U.S. Patent Publication No. US20120164200 and inU.S. patent application Ser. No. 13/905,429, each of which isincorporated herein by reference to the extent it does not conflictherewith.

Hydrophobic Coating

The hydrophobic component is a hydrophobic polymer that is dispersiblein water to form the basic elements of the hydrophobic properties of thepresent disclosure. In general, a hydrophobic component of thisdisclosure can include, but is not limited to, fluorinated orperfluorinated polymers. However, due to low degree of waterdispersibility, the fluorinated or perfluorinated polymer can need to bemodified by introducing a comonomer onto their molecular structure.Suitable comonomers include, but are not limited to, ethylenicallyunsaturated monomers including functional groups that are capable ofbeing ionized in water. One example is ethylenically unsaturatedcarboxylic acid, such as acrylic acid. The amount of the comonomerwithin the hydrophobic component is determined by balancing twoproperties: hydrophobicity and water dispersibility. One example of thehydrophobic component of this disclosure is a commercially availablemodified perfluorinated polymer compound available from DUPONT as awater-based product under the trade name CAPSTONE STC-100. Due to itslow surface energy, the polymer contributes to the hydrophobicity.Additionally, the polymer molecules can be modified to contain groups,such as amines, that can become charged upon pH reduction and alter thedynamics of hydrophobicity within the liquid dispersion. In such a case,the polymer can stabilize in water through partial interaction.Surfactants that are introduced into the composition can also behave asdispersants of the polymer, thereby also altering some of thehydrophobic mechanics. Hydrophobic coatings are further described inU.S. patent application Ser. No. 13/193,065, which is incorporatedherein by reference to the extent it does not conflict herewith.

The solid components of the present disclosure can be present in anamount from about 1.0% to about 3.0%, by weight of the solution. Such anamount is suitable for spray applications where higher concentrations ofpolymer can lead to either viscoelastic behavior, resulting in eitherclogging of the spray nozzle or incomplete atomization and fiberformation, or dramatic increases in dispersion viscosity and thus nozzleclogging. It should be noted that this range is not fixed and that it isa function of the materials being utilized and the procedure used toprepare the dispersion. When a higher amount of the polymer is used, thesurface structure is less desirable as it lacks the proper texture to behydrophobic. When a lower amount of the polymer is used, the binding isless desirable as the coating behaves more so as a removable powdercoating.

UNIDYNE KCO3 fluorinated water and oil repellent is composed of water,flouroalkyl methacrylate copolymer, emulsifiers, and tripropyleneglycol. It is a cost effective, soil resistant, oil and water repellantflouropolymer. The function of water and oil repellency is due toUNIDYNE KCO3 fluorinated water and oil repellent reducing the surfaceenergy. This reduction of surface energy is due to the fluorine that ispresent. Daikin UNIDYNE products have been investigated in the past andis currently used in, for example, surgical gowns.

DUPONT CAPSTONE STC-100 is an aqueous flourochemical dispersion thatprovides a transparent protective barrier against oil and water onporous surfaces.

FENNOSIZE BMP sizing is available from Kemira Chemicals, Helsinki,Finland. It is a water-dispersible surface sizing. POLYGRAPHIX sizing isalso available from Kemira Chemicals.

PRECIS 2090 sizing is an internal alkyl ketene dimer (AKD) sizing agentfrom Hercules Corporation. Internal sizing is also based on lowering thesurface energy of the cellulose. The bulk sizing technique includes anAKD molecule binding to the cellulose fiber.

Non-Organic Solvent

The formulation used in treating the surface of the present disclosureeliminates the use of an organic solvent by carefully selecting theappropriate combination of elements to impart the hydrophobiccharacteristics. Preferably, the non-organic solvent is water. Any typeof water can be used; however, demineralized or distilled water can beopted for use during the manufacturing process for enhancedcapabilities. The use of water helps to reduce the safety concernsassociated with making commercial scale formulations including organicsolvents. For example, due to the high volatility and flammability ofmost organic solvents, eliminating such use in the composition reducesproduction safety hazards. Additionally, production costs can be loweredwith the elimination of ventilation and fire prevention equipmentnecessitated by organic solvents. Raw material costs can be reduced inaddition to the transportation of such materials as an added advantageto utilizing the non-organic solvent formulation to arrive at thepresent disclosure.

The formulation used to treat the surface of the present disclosureincludes greater than about 95%, greater than about 98%, or about 99%water, by weight of the dispersion composition.

Other Optional Ingredients Binders

The hydrophobic polymers within the formulation of the presentdisclosure can play a dual role in acting both as a hydrophobiccomponent and a binder. Polymers such as DUPONT CAPSTONE STC-100 promoteadhesion, as compared to the fluorinated polymer alone, so that anadditional binder within the composition is not necessary. If awater-dispersible hydrophobic polymer is used wherein an additionalbinder is needed, it is preferred that the binder is selected fromwater-dispersible acrylics, polyurethane dispersions, acryliccopolymers, or acrylic polymer precursors (which can cross link afterthe coating is cured).

The amount of the binder present within the formulation of the presentdisclosure can vary. A binder can be included in an effective amount ofup to about 2.0% by weight of the total dispersion composition.

Stabilizing Agent

The formulation within the present disclosure can be additionallytreated with a stabilizing agent to promote the formation of a stabledispersion when other ingredients are added to it. The stabilizing agentcan be a surfactant, a polymer, or mixtures thereof. If a polymer actsas a stabilizing agent, it is preferred that the polymer differ from thehydrophobic component used within the base composition previouslydescribed.

Additional stabilizing agents can include, but are not limited to,cationic surfactants such as quaternary amines; anionic surfactants suchas sulfonates, carboxylates, and phosphates; or nonionic surfactantssuch as block copolymers containing ethylene oxide and siliconesurfactants. The surfactants can be either external or internal.External surfactants do not become chemically reacted into the basepolymer during dispersion preparation. Examples of external surfactantsuseful herein include, but are not limited to, salts of dodecyl benzenesulfonic acid and lauryl sulfonic acid salt. Internal surfactants aresurfactants that do become chemically reacted into the base polymerduring dispersion preparation. An example of an internal surfactantuseful herein includes 2, 2-dimethylol propionic acid and its salts.

In some aspects, the stabilizing agent used within the composition totreat the surface of the present disclosure can be used in an amountranging from greater than zero to about 80% of the hydrophobiccomponent. For example, long chain fatty acids or salts thereof can beused from about 0.5% to about 10% by weight based on the amount ofhydrophobic component. In other aspects, ethylene-acrylic acid orethylene-methacrylic acid copolymers can be used in an amount up toabout 80%, by weight based of hydrophobic component. In yet otheraspects, sulfonic acid salts can be used in an amount from about 0.01%to about 60% by weight based on the weight of the hydrophobic component.Other mild acids, such as those in the carboxylic acid family (e.g.,formic acid), can also be included in order to further stabilize thedispersion. In an aspect that includes formic acid, the formic acid canbe present in an amount that is determined by the desired pH of thedispersion wherein the pH is less than about 6.

Additional Fillers

The composition used to treat the surface of the present disclosure canfurther include one or more fillers. The composition can include fromabout 0.01 to about 600 parts, by weight of the hydrophobic component,for example, polyolefin and the stabilizing agent. In certain aspects,the filler loading in the composition can be from about 0.01 to about200 parts by the weight of the hydrophobic component, for example,polyolefin, and the stabilizing agent. It is preferred that such fillermaterial, if used, be hydrophilic. The filler material can includeconventional fillers such as milled glass, calcium carbonate, aluminumtrihydrate, talc, antimony trioxide, fly ash, clays (such as bentoniteor kaolin clays for example), or other known fillers. Untreated claysand talc are usually hydrophilic by nature.

Examples

The following are provided for exemplary purposes to facilitateunderstanding of the disclosure and should not be construed to limit thedisclosure to the examples.

Sample Fabrication. The following matrix of samples was created:

Chemistries Formula- Formula- FENNOSIZE POLYGRAPHIX PRECIS SubstratesUNIDYNE tion III tion V sizing sizing sizing Substrate B X X X X XSubstrate B + HYPOD dispersion X X X X X Substrate A X X X X X SubstrateA + HYPOD dispersion X X X X X Handsheets X Handsheets/PRECIS sizing X X

For the substrates that were coated with UNIDYNE KCO3 fluorinated waterand oil repellent, Formulation III, Formulation V, FENNOSIZE sizing,PRECIS sizing, and POLYGRAPHIX sizing were added onto at a low, medium,and high level. Low was approximately 1 gsm, medium was approximately 5gsm, and high was approximately 10 gsm. These chemistries were added onusing an atomizing sprayer and an Allen Bradley Panelview Controller550.

Recipes for each chemistry are as follows:

Cycle speed Approx- setting imate Substrate Formula (fpm) Passes gsmNanoclay on Substrate A + HYPOD dispersion Substrate A + Formulation V -56 4 1 HYPOD dispersion 6.5% PMC + 1.25% nanoclay + water Substrate A +Formulation V - 46 5 5 HYPOD dispersion 12.5% PMC + 2.5% nanoclay +water UNIDYNE KC03 on Substrate A + HYPOD dispersion Substrate A +KC03 - 30% 77 4 1 HYPOD dispersion Substrate A + KC03 - 100% 46 2 5HYPOD dispersion Substrate A + KC03 - 100% 46 4 10 HYPOD dispersionFormulation III on Substrate A + HYPOD dispersion Substrate A +Formulation III - 56 2 1 HYPOD dispersion 31.25% PMC + water SubstrateA + Formulation III - 56 5 5 HYPOD dispersion 31.25% PMC + waterSubstrate A + Formulation III - 56 2 10 HYPOD dispersion 62.5% PMC +water FENNOSIZE sizing on Substrate A + HYPOD dispersion Substrate A +FENNOSIZE 56 3 10 HYPOD dispersion sizing 80% Formulation III onSubstrate B Substrate B 5% Formulation III - 56 3 1 31.25% PMC + waterSubstrate B 5% Formulation III - 56 4 5 31.25% PMC + water Substrate B5% Formulation III - 56 5 10 62.5% PMC + water Nanoclay on Substrate BSubstrate B 5% Formulation V - 46 2 1 6.25% PMC + 1.25% nanoclay + waterSubstrate B 5% Formulation V - 46 5 5 12.5% PMC + 2.5% nanoclay + waterSubstrate B 5% Formulation V - 25% 46 5 10 PMC + 5% nanoclay + waterUNIDYNE KC03 on Substrate B Substrate B 5% 30% UNIDYNE KC03 90 1 1Substrate B 5% UNIDYNE KC03 46 1 5 Substrate B 5% UNIDYNE KC03 46 2 10Formulation III on Substrate B + HYPOD dispersion Substrate B +Formulation III - 56 4 1 HYPOD dispersion 6.25% PMC Substrate B +Formulation III - 56 3 5 HYPOD dispersion 62.5% PMC + water SubstrateB + Formulation III - 56 5 10 HYPOD dispersion 62.5% PMC + water UNIDYNEKC03 on Substrate B + HYPOD dispersion Substrate B + UNIDYNE KC03 - 77 11 HYPOD dispersion 30% Substrate B + UNIDYNE KC03 46 1 4 HYPODdispersion Substrate B + UNIDYNE KC03 46 2 10 HYPOD dispersion Nanoclayon Substrate A Substrate A Plain Formulation V - 6.5% 56 2 1 PMC + 1.25%nanoclay + water Substrate A Plain Formulation V - 25% 46 3 5 PMC + 5%nanoclay + water Substrate A Plain Formulation V - 25% 46 5 10 PMC + 5%nanoclay + water UNIDYNE KC03 on Substrate A Substrate A Plain UNIDYNEKC03 30% 56 3 5 Substrate A Plain UNIDYNE KC03 30% 56 3 10 FormulationIII on Substrate A Substrate A Plain Formulation III - 56 1 1 31.25%PMC + water Substrate A Plain Formulation III - 56 4 5 31.25% PMC +water Substrate A Plain Formulation III - 56 5 9 62.5% PMC + water

Substrate A and Substrate B samples were coated twice on each side usingthe following creping technique: the chemicals were foamed and thenapplied to the dryer surface. This creping technique improvesapplication efficiency by reducing waste because the chemistryapplicator can be placed in much closer proximity to the dryer surfacethan liquid spray tips (¼″ vs. 4″). Liquid and air was pumped into amixer that blends the air into the fluid and produces foam that containsfine bubbles. This foam exits the mixer and flows to an applicator thatis placed closely to the dryer surface to uniformly distribute the foam.

Handsheet samples were made with 70% Pictou Pulp and 30% EucalyptusPulp. The PRECIS sizing addition was added into the pulp water mixtureper the required concentration. The following PRECIS sizing handsheetswere created: Control: no PRECIS sizing, 2 lbs PRECIS sizing/MT pulp, 4lbs PRECIS sizing/MT pulp, 8 lbs PRECIS sizing/MT pulp, 16 lbs PRECISsizing/MT pulp, 32 lbs PRECIS sizing/MT pulp. A set of handsheets witheach level of PRECIS sizing add-on was then spray coated with UNIDYNEKCO3 fluorinated water and oil repellent chemistry and another set withFormulation V.

Drop Test

The drop test was the initial screening method for these samples. A dropof water was placed on the sample and a stop watch was started. When thesample penetrated or was absorbed, the stop watch was stopped and thetime was noted. If the drop penetrated in under 60 seconds, thosesamples were discarded. If a drop stayed at least 60 seconds, then thosesamples were tested with Functional Water Barrier Testing and Hydrohead.Samples that had to be eliminated via this technique were all substratesthat had been treated with POLYGRAPH IX sizing chemistry and substrateswith low add-ons of the FENNOSIZE sizing chemistry. Substrates that werecoated with only HYPOD polyolefin dispersion also did not pass thistest.

Hydrohead

Hydrohead was measured with hydrohead equipment that was created in theUniversity of Illinois in Chicago. Water is pumped into a column gradedfor centimeters of water. The sample is attached to the bottom of thecolumn, treated side toward the water. A mirror is placed on theunderside of the sample. When the first drop is visualized, the valve isclosed and the height of the water is recorded. FIG. 9 shows an image ofthe apparatus.

Data shows that hydrohead trend can increase slightly with add-on levelbut is mainly dictated by substrate. HYPOD polyolefin dispersion coatedSubstrate A and Substrate B generally have higher hydrohead thannon-HYPOD polyolefin dispersion coated samples. FIG. 1 shows hydroheadtrends for these substrates. Handsheets increase in hydrohead as sizeconcentration is increased and then decreases. FIG. 2 shows the effectof bulk sizing on the handsheets.

Functional Water Barrier Testing

The purpose of the Functional Water Barrier Test is to help determinethe ability of treated substrates to withstand insults of water meant toreplicate a baby's urine. The test is done by placing a piece of blotterpaper beneath the treated substrate. A diaper core is placed atop thesubstrate and insulted with saline. A weight is then placed on thediaper core and left to rest for 15 minutes. The blotter paper is thenweighed and compared to its starting weight to determine the substrateseffectiveness.

Steps to Follow

-   -   1) Weigh blotter papers and diapers cores. Record measurements        in spreadsheet. Keep as matched pairs for proper calculations.    -   2) Fill syringes with total of 127 ml per sample, three samples        per code.    -   3) Layer blotter paper, treated substrate within plastic shield        and diaper cores.    -   4) Insult sample with 127 ml of saline and start timer for 15        minutes.    -   5) Wait one minute and place weight on top of stack.    -   6) Repeat process for next two samples.    -   7) Weigh blotter papers at end of 15 minutes.

It was found that there were three regimes of water barrier with thiskind of testing: “No barrier”—where the saline permeated the outer coversample; “Barrier: Feels Clammy”—where the amount of saline thatpermeated the outer cover was so low it was more of a water vaportransmission; and “Barrier: feels dry”—where the amount of saline thatpermeated the outer cover was either none or was so low that it was notdetectable by touch, only by gravimetric analysis. FIGS. 3 and 4 showthe Substrate A and Substrate B based samples that fell into theregimes. FIG. 5 shows the functional water barrier test behavior forhandsheets. Handsheet barrier falls from no barrier to “feels clammy”with the smallest sizing amount and then slightly increases but stays inthat “feels clammy” regime. Handsheets with hydrophobic chemistries inaddition to the sizing fall into the same “feels clammy” regime, evenwith zero sizing. The hydrophobic add-ons were approximately 0.1 gsm forNanoclay and 2 gsm for UNIDYNE KCO3 fluorinated water and oil repellent.

Air Permeability

The samples were tested for air permeability. The air permeabilitytesting was Standard Test Method (STM) EQ-STM-3801: “AirPermeability—Tesxtest FX 3300.” It was found that like hydrohead, airpermeability depended mainly on the type of substrate. FIG. 6 shows airpermeability for different samples. Substrate B basesheets withhydrophobic chemistries had the most permeability, then Substrate Asamples, and then any samples that were coated with polyolefindispersion and hydrophobic chemistries. Handsheets had the least amountof air permeability. The air permeability of a standard ASFL outer coveris zero.

Analysis

The typical test method to understand the water barrier behavior fordiapers is hydrohead. For an outer cover material that provides anadequate water barrier but not necessary a premium water barrier, thehydrohead to be achieved can potentially be much less than the hydroheadof standard premium ASFL outer covers, which was found to beapproximately 137 cm of water. Hydrohead is essentially a very robusttest that couples strength and impermeability. For an outer cover samplethat has been designed for water barrier and not strength, hydroheadmeasurement can be somewhat of an excessive evaluation that does notnecessarily describe the impermeability function. As a result, thefunctional water barrier test was designed. When hydrohead is plottedagainst functional water barrier test leakage it can be seen thathydrohead does not necessarily describe all cases of water barrierfunctionality. For the materials described herein, high hydrohead wasalways equal to low leakage; high leakage was always equal to lowhydrohead; but low hydrohead was not equal to high leakage. Lowhydrohead could have high or low leakage. FIG. 7 illustrates thisrelationship. Note that the functional water barrier test that thesehydrohead values were plotted against were carried out in a slightlydifferent way than those in FIGS. 3, 4, and 5. The pressure wasincreased to 0.2 psi, the core was insulted with saline to 90% of itscapacity, and a one-minute wait was provided for the absorbent core tobegin to absorb the saline before adding the weight.

Air permeability demonstrated a similar behavior that can be seen inFIG. 8. High and medium air permeability always had low hydrohead;however, samples that had low air permeability varied in hydrohead. Thisis suspected to be due to the presence of larger pore openings. Samplesthat had low permeability were those coated with a polyolefin dispersionor were the very dense handsheets. Substrate B had more air permeabilitythan Substrate A.

The presence of pores not only dictated the air permeability, but alsoseemed to affect the leakage barrier in the FWBT results shown in FIGS.3 and 4. It can be seen in both figures that tissue coated with apolyolefin dispersion and a hydrophobic chemistry shows a better leakagebarrier than the tissues that only have the hydrophobic chemistry.Because of this behavior it is suspected that the water barrier can beachieved by a combination of two mechanisms: surface energy reduction(from the hydrophobic chemistries) and pore clogging (by the polyolefindispersion coating). Each one of those was not sufficient on its own tocreate a barrier that felt completely dry.

As described herein, it is possible to create a tissue based waterbarrier that can be used as an outer cover. A combination of apolyolefin dispersion and hydrophobic/superhydrophobic chemistries canbe used to achieve this result. The combination was seen to provide amore uniform treatment of the surface. Such uniformity is important whenthe function of interest is a barrier because a single weak point cancause the failure of an entire substrate. Prior efforts have focused ontreating a basesheet with either a polyolefin dispersion or ahydrophobic/superhydrophobic chemistry. The combination found hereinyields unexpected benefit.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

All documents cited in the Detailed Description are, in relevant part,incorporated herein by reference; the citation of any document is not tobe construed as an admission that it is prior art with respect to thepresent disclosure. To the extent that any meaning or definition of aterm in this written document conflicts with any meaning or definitionof the term in a document incorporated by reference, the meaning ordefinition assigned to the term in this written document shall govern.

While particular aspects of the present disclosure have been illustratedand described, it would be obvious to those skilled in the art thatvarious other changes and modifications can be made without departingfrom the spirit and scope of the disclosure. It is therefore intended tocover in the appended claims all such changes and modifications that arewithin the scope of this disclosure.

What is claimed is:
 1. A hydrophobic, liquid-impermeable substratecomprising: a hydrophilic nonwoven having a treated surface; apolyolefin dispersion disposed on the treated surface; and a hydrophobicchemistry disposed on the polyolefin dispersion.
 2. The substrate ofclaim 1, wherein the hydrophilic nonwoven includes tissue or papertoweling.
 3. The substrate of claim 1, wherein the hydrophilic nonwovenincludes cellulose.
 4. The substrate of claim 1, wherein the hydrophilicnonwoven includes fibers.
 5. The substrate of claim 1, wherein thesubstrate is breathable and exhibits an air permeability of 100 cfm. 6.The substrate of claim 1, wherein the hydrophilic nonwoven includes ahydrophilic surface opposite the treated surface.
 7. The substrate ofclaim 1, wherein the hydrophobic chemistry is a water-dispersiblehydrophobic polymer.
 8. The substrate of claim 1, wherein thewater-dispersible hydrophobic polymer includes a comonomer selected fromacrylic monomers, acrylic precursors, and the like.
 9. The substrate ofclaim 1, wherein the hydrophobic chemistry is a superhydrophobicchemistry.
 10. The substrate of claim 9, wherein the superhydrophobicchemistry includes a hydrophobic component selected from the groupconsisting of fluorinated polymers, perfluorinated polymers, andmixtures thereof.
 11. The substrate of claim 9, wherein thesuperhydrophobic chemistry includes one of UNIDYNE KCO3 fluorinatedwater and oil repellent or the Formulation III chemistry.
 12. Thesubstrate of claim 1, wherein the polyolefin dispersion is HYPOD 8510.13. The substrate of claim 1, further comprising nanoclay.
 14. Thesubstrate of claim 1, the further comprising a surfactant, wherein thesurfactant is selected from nonionic, cationic, and anionic surfactants.15. The substrate of claim 1, further comprising a stabilizing agentselected from the group consisting of long chain fatty acids, long chainfatty acid salts, ethylene-acrylic acid, ethylene-methacrylic acidcopolymers, sulfonic acid, acetic acid, and the like.
 16. The substrateof claim 1, further comprising a filler selected from the groupconsisting of milled glass, calcium carbonate, aluminum trihydrate,talc, antimony trioxide, fly ash, clays, and the like.
 17. A method forpreparing a hydrophobic, breathable, liquid-impermeable substratecomprising: providing a hydrophilic nonwoven having a treated surface;applying a polyolefin dispersion to the treated surface; and applying ahydrophobic chemistry to the polyolefin dispersion.
 18. The method ofclaim 17, wherein the hydrophilic nonwoven includes tissue or papertoweling.
 19. The method of claim 17, wherein the hydrophobic chemistryis a water-dispersible hydrophobic polymer.
 20. The method of claim 17,wherein the hydrophobic chemistry is a superhydrophobic chemistry.